Non-volatile memory (NVM) retains stored data even after the power is turned off. The most widely used type of NVM has been flash memory. However, flash memory has to be written in larger blocks than typical computers can automatically address, and typically only lasts for a finite number of write-erase cycles before deteriorating. Newer types of NVM offer better performance while maintaining the non-volatility aspect of flash memory. These technologies include, for example, memristors, phase change memory (PCM), and spin-torque transfer RAM (STT-RAM).
Memristor devices are based on resistance switching effects, and allow greater data density than hard drives with fast access times. PCM devices handle read/write operations based on changes in electrical resistance, offering high storage density. STT-RAM devices “flip” the active elements used in magnetic random access memory (RAM), and offers lower power consumption with better scalability.